\documentclass{article}

\usepackage{pgfplots}

\pgfplotsset{compat=1.14}

\begin{document}

\begin{tikzpicture}
	\begin{axis}[colormap name=viridis,colorbar]
	%\tracingmacros=2 \tracingcommands=2
	\addplot3[contour filled={levels={-75,4,5,6,50,250},
	}]
	{x^2*y};
	\end{axis}
\end{tikzpicture}
\end{document}

